1. Field of the Invention
The invention relates to a touch apparatus, a method for determining a position, and a touch system, and particularly relates to an optical touch apparatus, a method for determining a position of a touch indicator point, and an optical touch system.
2. Description of Related Art
Generally, optical touch systems can be classified into two types, namely a blocking type and a non-blocking type. A blocking optical touch system is based on the principle of signal blocking that a touch object blocks a light signal emitted from a light source (e.g., a string of light emitting diodes or a reflective strip), and optical sensors in the blocking optical touch system sense a shadow having a lower brightness relative to the background of the touch object, such that an occurring position of the touch object and its corresponding touch operation can be determined. On the other hand, a non-blocking optical touch system usually includes an optical touch stylus or the use of a finger which is configured to perform a touch operation on a touch surface so as to transmit a light signal to the optical sensors. For example, in the non-blocking optical touch system using the optical touch stylus, according to the type of the optical touch stylus, the light signal transmitted from the optical touch stylus to the optical sensors may be actively generated from the internal of the optical touch stylus, or generated by the optical touch stylus reflecting back the light signal transmitted by a light source attached to the optical sensor. Therefore, the optical sensors can determine the occurring position of the touch object and its corresponding touch operation according to the received light signal having a higher brightness relative to the background.
However, the optical touch stylus may generate a mirror image on the touch surface (e.g., when the touch surface is a white board) when the optical touch stylus is operated on the touch surface. Since the properties of the mirror image may differ as factors such as the material of the touch surface and the positions of the optical sensors relative to the optical touch stylus differ, the optical sensors may not be able to accurately determine the position of the tip of the optical touch stylus or the touch indicator point after receiving an optical signal, making the touch system less convenient to use. For example, when the determined position of the tip of the stylus is too low, a touch response is generated when there is still a certain distance between the optical touch stylus and the touch surface, and when the determined position of the tip of the stylus is too high, the connection of the optical touch stylus on the touch surface may be disconnected.